It is possible to recover the familiar expression for the tensor equation [1]} for the limiting case \(\varepsilon \rightarrow 0\) . Following a development of the Navier-Stokes equations found in the aerodynamic sound literature [2]}, [3]}, [4]} taking the time derivative of the continuity equation for the probability density (4) and the divergence of (24) and subtracting them we can eliminate the convection term. In that way we combine the two in a new exact form as
\(\frac{\partial ^{2}\rho }{\partial t ^{2}}+\frac{2\varepsilon }{m\hbar }\frac{\partial (\rho Q v_{i})}{\partial t} =\frac{\partial ^{2}}{\partial x_{i}\partial x_{j}}\left(\rho v_{i}v_{j}-\frac{\rho }{m} V\delta _{ij}+\sigma _{ij}\right),\) 
